1. Field of the Invention
The present invention relates to a backlight adjustment device which adjusts brightness of a backlight of an image display device provided in a camera-equipped terminal, and the terminal.
2. Description of the Related Art
In the past, in order to reduce power consumption, an approach of adjusting a liquid crystal backlight based on an output result of an element for detecting brightness such as a luminance sensor has been employed.
If an element for detecting brightness is further added to a camera-equipped cellular phone or personal computer, the system, cost, and dimensions of the device will inevitably increase.
Document 1 (Jpn. Pat. Appln. KOKAI Publication No. 2001-223792) discloses a technique of detecting a luminance of a marginal environment using an image sensor and controlling on/off switching of a liquid crystal backlight based on the detected luminance.
Document 2 (Japanese Patent No. 3882522) discloses a camera-equipped portable terminal which controls brightness of a display means, using at least one of a shutter speed and a gain value of an imaging means, and a photometric result of a photometric means which performs photometry based on output data from the imaging means. The portable terminal turns off the backlight if the shutter speed exceeds a predetermined value, and turns on the backlight if the shutter speed is less than or equal to a predetermined value.
When an image sensor is used as above, a detection result may not be determined with high accuracy unless the exposure time is adjusted.